migrate-wp-user-avatar.php

<?php
/*
Migrate from WP User Avatar to Simple Local Avatars

Allows sites to easily move away from the WP User Avatar plugin and switch to Simple Local Avatars instead.

Run by invoking with WP CLI like so:
	`wp eval-file migrate-wp-user-avatar.php`

Author: Philip John
Author URI: http://philipjohn.me.uk

License: GPLv2
*/

// Get the name of the meta key for WP User Avatar.
global $wpdb;
$meta_key = $wpdb->get_blog_prefix() . 'user_avatar';

// Grab all users that have a local avatar.
$users = get_users( [
	'meta_key'     => $meta_key,
	'meta_compare' => 'EXISTS',
] );

foreach ( $users as $user ) {
	// Get the existing avatar media ID.
	$avatar_id = get_user_meta( $user->ID, $meta_key, true );

	// Attach the user and media with Simple Local Avatars.
	$sla = new Simple_Local_Avatars();
	$sla->assign_new_user_avatar( (int) $avatar_id, $user->ID );

	// Check that worked.
	$sla_done = get_user_meta( $user->ID, 'simple_local_avatar', true );
	if ( ! empty( $sla_done ) ) {
		// Remove the old WP User Avatar meta data.
		delete_user_meta( $user->ID, $meta_key );
	}
}

I get a fatal error:

Fatal error: Uncaught Error: Call to a member function get_blog_prefix() on null in /public_html/wp-content/migrate-wp-user-avatar.php:18 Stack trace: #0 {main} thrown in /public_html/wp-content/migrate-wp-user-avatar.php on line 18

Anyone who can help?

@philipjohn I received a report of this failing on multisite, where the script only works on the main site and not subsites. Is that a known issue, something that needs to be accounted for in running the script differently, or a user mistake?